Telephonic apparatus.



E. A. GRAHAM.

TELEPHONIC APPARATUS.

APPLICATION FILED JULY 28.1910.

Patented Mar. 19, 1912.

6 SHEETS-SHEET 1 E. A. GRAHAM.

TELEPHONIU APPARATUS.

APPLICATION FILED JULY 23, 1910.

1,020,898 Patented Mar. 19, 1912.

6 BBEETS-SHEIIT 2.

//IIIIIIIIIIII' E. A. GRAHAM.

TELEPHONIG APPARATUS.

APPLICATION FILED JULY 28, 1910.

1,020,898. A Patented Mar. 19,1912.

6 BHEET8-BHEET 3.

E. A. GRAHAM.

TELEPHONIC APPARATUS.

APPLICATION FILED JULY 28, 1910.

1,020,898, Patented Mar. 19, 1912.

6 BHEETSBHEET 4.

E. A. GRAHAM.

TELEPHONIC APPARATUS.

APILIOATION'IILED .TULY28,1910.

Patented Mar. 19, 1912.

6 SHEETS-SHEET 5.

E. A. GRAHAM.

TELEPHONIG APPARATUS.

APPLICATION FILED JULYZB, 1910.

LGQQBQB. Patented Mar. 19, 1912.

6 SHEETS-SHEET 6.

' ED STATES PATENT OFFICE.

TELEPHONIC Specification of Letters Patent.

Application med July 28,

APPARATUS.

Patented Mar. 19, 1912. 1910. Serial No. 574,359.

To all whom it may concern:

Be it known that I, EDWARD ALrnno GRA- HAM, a subject. of the King of Great Britain and Ireland, residing at Brockley, in the county of London, England, have invented Improvements in or Relating to Telephonic Apparatus, of which-the following is a specification.

This invention relates to water tighttelephonic apparatus of the now well known kind in which the transmitter and receiver and the switch and electrical connections are mounted Within a single casing, and it has for its object to effect certain detail improvements tending, individually, to secure even greater reliability, etficiency and simplicity than heretofore, and collectively producing a complete loud speaking instrument which can be connected in circuit to receive and transmit calls by voice and by a distinctive callin device, alternatively, as hereinafter set orth.

In the accompanyin'g'drawings, Figure 1 is a front elevation and. Fig. 2 a side elevation of one construction of instrument em,- bodying the invention. Fig. 3 is a front elevation of the instrument as it appears when open and Fig. 4 is a horizontal section taken on the line AB of Fig. 3, the instrument however being partly closed. Fig. 5 is a section to a larger scale of a dctail of Fig. 4. Fig. 6 is a side elevation of a portion of the receiver of theinstrument shown in Fig. 4 and Fig. 7 is a diagram pertainin thereto. Fig. 8 is a view corresponding to Fig. 3 illustrating a modificatlon. Fig. 9 is a diagram showing the mode of connecting together two instruments, and the internal wirlng thereof, one instrument being of the form according to Figs. 1 to 5 and the other instrument of the modified form according to Fig. 8. Fig. 10 is a diagram with the aid of which the mode of operation of the system can be more easily described.

Referring first to Figs. 1 to 7 inclusive, a isthe case which, in known way, is provided with supporting means I) for minimizmg transmission of shock .to the apparatus, but which in accordance with the present invention is formed with a separate junction boir 0 having a removable cover d so that access can be easily obtained to the terminals for the incoming line wires for testing of cables or of the apparatus, wlthout opening the main cover e of the instrument, The

terminals in the box 0 are four in number shaped that the user may speak very closely into the instrument and concentrate the sound on to the diaphragm of the transmitter. Thetransmitter, which is of the carbon granule type, is preferably protected by a grating 2', but in lieu of this being stationary, as heretofore, it forms part of a shutter plate 7' that normally acts to close the inner endof the mouth piece 72. (see Figs. 1 and 4) and is moved to bring the gratin into register with such end of the mout piece only by operation of the hand lever is of the switch that serves to put the transmitter and receiver in circuit. For this purpose, the mouth piece It may be formed with a housingm (Fig. 4') to receive the plate 9' which is pivoted thereto at n and has a bifurcated portion 0 enga ed by a lug p on the lever is. As will be 0 vious, the shutter plate j affords morecomplete protection to the transmitter diaphragm than the grating would when the instrument is not in use. The transmitter comprises, as shown more particularly in Figs. 4 and 5, a carbon diaphragm g and a protective diaphragm 53 of mica or the like held in contact in a bein subjected to uneven stresses such as obtain when the parts 7 by screws and w ich roduce strains that affect the efficiency of t e transmitter. For this purpose, the packing rings between which the diaphragms are clamped are held in position by a rin "forced into the diaphragm holder. In t e example illustrated, the mica diaphragm 53 abuts directly against a washer 54 of more or less elastic 0r yieldin. material held in position by means of t e'flange 55 of a metal ring 56 constituting art of the diaphragm ho der A ring 57 0 thin sheet metal, for example copper, is placed against the rear side of the carbon diaphragm a washer 58 of mica is placed against t e metal ring and then,a second washer 59 of insulating material similar to the washer 54 is laced against the mica washer 58, the hol er beholder in such a manner as to prevent their.

are secured together has a sound director or mouth piece It so ing completed by forcing into the ring 56 a metal ring 60. The ring 56 is provided at 81 with an annular lining of insulating material, for example a strlp of mica, to prevent the diaphragm 9 making peripheral contact with such ring, and the holder when complete may be given an application of waterproof paint or enamel at the region marked 62. The metal ring 57 is provided with a strip-like extension 63vfor connecting up the ring 57, and-consequently the carbon diaphragm g, in the circuit of the transmitter. The arrangement is such that complete water and air tightness is secured, while the diaphragms g and 53 are clamped with an equahpressure all around so that no strain is imposed upon either of them. It

will be seen that electrical leakage from the diaphragm g is efiectually prevented by the outer diaphragm 53 thus enabling the insulation resistance to, be maintained and avoiding the possibility of faults occurring by accumulation of moisture between the diaphragm q and the holder 5556. The transmitter is provided with a rear electrode r which, while revoluble to secure the well known efiect of agitating the carbon gra ules 1- in contact with it and the diaphra i q, is operated in a special manner from ti o switch hand lever b so that it is rotated in termittently in one direction only, that is to say, it is moved with movement of the hand lever to close the switch but not when opening the switch. The result is that the wear of the felt or like material of the granule retaining rings (Fi at) is materially reduced This intermlttent rotation of the electrode r is efiect-ed by fitting upon the carrying spindlet oi? the electrode 7* a sleeve a having'ratchet teeth '1: adapted to be engaged. by a pawl w (Figufi) pivoted within the box. portion w of a switch member 3 movable upon the sleeve uand closed by a cover. plate .2 (Fig, 4:) carrying a'contact pin 3 and a carbon block l, The member g carries an insulated pin '5 which engages a slot 6 in a lever 7 secured to the switch spindle 8 which is encircled by a spring 9 to return the parts to the position illustrated after they are moved therefrom by" operation of the lever is. The stationary-switch member comprises a pair of spring blades 10, cotiperating with the contact pin 3,, and a carbon block 11 carried by a spring blade 12 for coi'iperationwith the carbon block i, the arrangement being such that the initial make and final break take place between the carbon blocks i and 11.,

To resist turning movement of the rear electrode in a direction reverse to that in which it is positively driven. by the ratchet and pawl mechanism, a cupped spring washer 18 may be provided to act as a brake, the said washer bearing against a plate 13 fixed to the baclr of the holder or casing 13 masses of the transmitter. A hell or call push I l and three terminal-pins 15, 16, 17 essentially complete the cover equipment, a

The receiver mechanism in the case a comprises a diaphragm 18 which, with its lever system, is given an initial mechanical stress in order to secure increased loudness and clearness of tone, As shown more par ticularly in Figs. 3,4- and 6, the diaphragm 18 is rigidily attached. at its central portion to one end of a lever 64: which is pivoted at 65- to the bifurcated extremity of one limb of a1 perina-nentmagnet 19, the extremity of the other limbof suchmagnet being pro: vided with an en'dwiseadjus'table pole piece 66 surrounded by an 'electromagneticwinding 67. The limb to which the pole piece 66 is applied is longer than the other limb of the magnet 19 and the lever 64; being polarized, by reason of its connection to the magnet, is attracted to the pole piece 66 with a force adjustable by altering the position of thepole piece 66. The initial mechanical stress referred to may be applied, as shown for example in Fig. 7, by displac'ingthe fulcrum 65-slightly in the direction of the arrow 68 from the position it would assume were the diaphragm 18 to occupy the full line position, with the result that, the diaphragm is distorted somewhat as is indicated, to an exaggerated scale, by the dotted lines. In use, the variation in strength of the line current will energize the electromagneticwinding 67 to varying extents and so augment to di erent degrees the me chanical stress initially imparted to the diaphragm 18 and produce the required vibrations with a much better definition of speechblade contact terminals 23, 24 25 cotiperating respectively with the terminal pins 15, 16, 17 of the cover, A. spring 26, carrying a carbon block 26*, extends, from the blade terminal 23 and a similar spring 27 carrying acarbon block extends from the terminal block 28, the carbon blocks of both. springs being adapted to be bridged by corresponding carbon blocks on a contact lever 29 cooperating with the call push 14c. The lever 29 is hinged at 30 to a support on theblock 21 and is normally held in open position by a suitable spring, not shown. On the block 22 are mounted a buzzer or interrupter 31 affording a distinctive'call note, and two terminals 32, 83;

lit will now be convenient to continue the description with reference to the diagram Fig. 10. Assuming that it is desired to call attention at station Y when the user at stavtion X requires to communicate therewith,

then the call. push 14 at station X is depressed to cause the carbon blocks of the springs 26, 27- to be bridged by the lever 29. A. circuit is thus completed rom the positive. supply line .34 through the inductance 35, sprlng 26 and lever 29 to the terminal 36 the negative supply line 39. In order that lever k and transmitter the fluctuations ofthe current may not be damped by the inductance 35, the circuit containing the buzzer 31 and the rec'eiver 38 is paralleled by a shunt resistance 40 connected between terminals 27 and 32 of the instrument at station X. The resistance 37 in addition to preventing sparking, maintains a small constant current through the circuit so that relays or other signal ear associated with say an exchange switc board may be positively operated. The noise of the buzzer in the instrument at station X can be plainly heard and aifords an indication that the receiver 38 at station Y is re ceiving the call current.

By operation of the switch lever (Fig. 1), a. voice call can be given as'the receiver 38 is always invcircuit. In speaking, the current will flow through the inductance 35, the switch 70 k is closed by the switch of the instrument at station X and the receiver 38 at station Y and thence to the negative-line 39. At the switch 7c 7c of the instrument at station X, a shunt circuit to thetransmitter g and receiver 38-is provided by a' resistance 41, so that the fluctuations set up by the transmitter q are reproduced in the receiver 38 of the instrument at station Y with full efficiency irrespective of the value of the inductance 35.

The operations for calling and conversation described as originating from station X to station Y appl to the corresponding circuits from station h to station X.

The mode of effecting the internal connections of the instruments will now be intelligible with the aid of the diagram Fig. 9.

When the apparatus is employed on a non-inductive circuit, such as when a' battery is used, the resistances 40 and 41 are disconnected.

The instrument shown in Fig. 8 difi'ers only from that described with reference to Figs. 1 to 7 inthat two hearing tubes are em 10 ed, one 47, of which is adapted to roc t e switch spindle 8 through a forked member 48 pivoted within the case a at 49 and engaging a roller 50 on the switch member y.

In a direct working arrangement, such as shown in Fig. 10, in which a transmitter g in one instrument is placed in series with a receiver .38 in a distant instrument, a relay 51 may be connected across each receiver to close a circuit across the positive and negative conductors throughan indicating device, as for example an incandescent electric lamp 52, for the purpose of indicating, where several instruments are located near together, from which of them the calling sound is proceeding.

What I claim is '1. A loud speaking telephone instrument, comprising a casing having a stationary mouth piece, a transmitter and a receiver in such casing, a revoluble rear electrode cooperating with the transmitter diaphragm, a switch for connecting the transmitter in circuit when conversation is desired, means operated by the switch and adapted, while the switch is being closed, to rotate the rear electrode but only While the switch is being closed, a buzzer inside the casing and a push operated from without the casing for connecting the buzzer in a call circuit.

2. In a telephone instrument, a transmitter and receiver adapted at one end to be connected respectively to separate electric supply mains and at the other end to separate lme wires for connection to a separate instrument, a distinctive calling device comrising an automatic circuit maker and reaker adapted to be connected to one of said line wires and a switch device for connecting said device to a supply main. 5

3. In a telephone instrument, a transmitter and receiver adapted at one end to be connected respectively to separate electric supply mains and at the other end to separate llne wires for connection to a separate instrument, a distinctive calling device comprising an automatic circuit maker and reaker adapted to be connected to one of said line w1res,a resistance connected in shunt to said device, and a switch device for connectin said devlce to a supply main.

4. A. te ephone instrument comprising a transmitter and receiver adapted at one side to be connected to separate line wires, a resistance connecting the other or second sides of said transmitter and receiver, a switch for connecting the secondside of the transmitter to one of the supply mains of an inductive circuit, the second side of the receiver bein adapted to be connected to another electric supply main of said circuit, a second resistance connected to said second side of said receiver, a distinctive calling device adapted to be connected on one side to the line wire for connection with the telephonic receiver of a distant instrument and a switch for connecting the other sideof the said device to the supply main to which the second side of said transmitter is connected and to the second resistance.

5. In a telephone instrument, a casing, a

transmitter and receiver therein the transelectrode and move the shutter plate so as to bring its grating into register with the mouthpiece. v

6. A loud speaking telephone instrument, comprising a casing having a stationary mouth piece, a transmitter with diaphragm behind the mouth piece, a revoluble rear electrode cooperating with the transmitter diaphragm, a receiver, a shutter plate disposed between the mouth piece and the transmitter diaphragim'a switch for conne'cting'the transmitter in circuit when conversation'is desired, means operated by the switch and adapted, while the switch 18 being closed, to rotate the rear electrode but only while the switch is being closed, and

-means also operated by the switch formovin g the shutter plate soithat the grating portion is brought into register with the mouth piece while speaking.

7 A loud speaking telephone instrument, comprising a casing having a stationary mouth piece, a transmitter with diaphragm said rear electrode, a ratchet wheel behind the mouth. piece, hearing means communicating with the casing, a receiver between the hearing means and casing, a revoluble rear electrode cooperating with said transmitter diaphragm, a spindle fixed to fixed to the spindle, a switch comprising fixed and movable members for connecting said transmitter in circuit, said movable switch member being mounted to oscillate about said spindle, a switch member and engaging said ratchet wheel and-switch operating mechanism connected to the said movable switch member. 8. A loud speaking telephone instrument, comprising a casing having a stationary mouth piece, a transmitter with diaphragm behind the mouth piece, a-receiver, a revoluble rear electrode cooperating with said transmitter diaphragm, a spindle fixed to said rear electrode, a ratchet wheel fixed to the spindle, a switch comprising fixed and movable members for connecting said transmitter in circuit, said movable switch member being mounted to oscillateabout said spindle, a pawl carried by said movable switch member and engaging said ratchet wheel and switch operating mechanism connected to the said movable switch member. Signed'at London England this 24th day of June1'910.

EDWARD ALFRED GRAHAM.

Witnesses:

EDMUND EUGENE BARNAR'D, HENRY WILLIAM DIPROSE.

pawl carried by said movable 

